109Ag 29 34 29 2) Give the electron configuration for the following elements, both the full configuration and using the noble-gas abbreviation, and then give the formula of the most common ion, along with its electron configurations. The first one is done as an example. Ion Electron Configuration Full Electron Configuration Full Ion formula Element Noble-Gas Noble-Gas INel Na (Sodium) 1s22s22pe3st INel3s Nat Al (Aluminum) S (Sulfur) N (Nitrogen) Ca (Calcium)

(c) Consider the semi-classical model for a two-electron atom illustrated in the diagram below. This model attempts to extend the Bohr model to a two-electron system by assuming both electrons follow a circular orbit around the nucleus while remaining diametrically opposite to each other. electron nucleus, electron (i) Carefully explain why, for the ground state of helium, this semi-classical model predicts that both electrons would experience an effective nuclear charge Zeff %3D (ii) Assuming that each electron's angular momentum is quantized in the same manner as the usual Bohr model for single-electron atoms, calculate the total binding energy of the ground state of helium according to this semi classical model.